What are the motifs in The Lady in the Lake by Raymond Chandler?

The recurring idea of good versus evil is seen in Chandler's presentation of Degarmo and Patton, particularly in the last chapters of the book. Patton is depicted as a good old boy, the epitome of small town law enforcement. He works as deputy, constable, firefighter, and other position where he might be needed in his jurisdiction. Although he does not show his intelligence, he obviously has a good idea of people work as he stakes out in Bill Chess's cabin waiting for Marlowe to break into the house looking for clues. Patton tells Marlowe he generally believes the simplest explanation of any crime is generally the correct one.